Dehumidifiier cascade  system and process

ABSTRACT

A dehumidification system is provided having a first cooling system which provides a sensible cooling effect and having its delivery enter a second system, in which air is favorably preconditioned using a pre-cooling upstream from and prior to dehumidification. A second unit having its own cooling element combined with an air to air heat exchanger in recovering the sensible cooling energy provides dehumidification through a dehumidification system in a cascade arrangement downstream to an air conditioning system. Pre-cooling is provided

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority to U.S. Provisional Patent Application No. 62/974,082, filed on Nov. 15, 2019, entitled “[ ],” and U.S. Provisional Patent Application No. 63/204,358 filed on Sep. 29, 2020, entitled “[ ],” the entire disclosures of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

The control of humidity in indoor environments plays a very important role in providing indoor air quality. Reducing the volume of moisture indoors can reduce the growth of microbiological organisms such as mold, mildew and bacteria, which require moisture to thrive. Airborne contaminants are also often carried with the moisture in the supplied air streams. Most conventional air conditioning processes and systems do not effectively control humidity. Although conventional systems provide dehumidification, this dehumidification is an uncontrolled byproduct of its evaporator coil cooling process, resulting in inadequate control of humidity, excessive energy consumption, and possible building and/or building space content damage.

Dehumidifier systems are designed to provide dehumidification. However, as air is passed over the dehumidifier's condenser coil, the air is also warmed—often to an extent above the temperature of its intake to the dehumidifier. In a cooling mode, an air conditioner must re-cool the air that was heated by the condenser in order to have an optimized cooling effect. Consequently, a dehumidifier does not typically enhance the cooling efficiency of, for example, a central air conditioner.

It would be desirable to have a dehumidification system that could provide dehumidification without the aforementioned air heating. Dehumidifiers are typically rated for the energy consumption. However, they are not rated in terms of energy savings provided on the central air conditioning cooling cost. In general, the challenge of dehumidification lies in reaching first the dew point, after which no dehumidification occurs, otherwise. Further, the energy required to reach the dew point accounts for the most needed for the total dehumidification system and process.

The second challenge is reaching a low dew point which is very difficult with cooling coils simply because the cooling coils often freeze below the freezing point. Also, considering that at low dew point refrigerant type system loses exponentially their energy effectiveness.

Conventional desiccant rotor technology typically incorporates a rotating desiccant wheel that rotates between two air streams to provide dehumidification or humidification by alternating the energy in a gas phase change process. In such systems, the process air delivered to the interior of a space to be conditioned crosses the desiccant material, which attracts and holds moisture. As the desiccant wheel rotates, the moist desiccant material enters the regeneration air stream where it is heated to release moisture, which is then vented away. Because humidity is a function of vapor pressure, desiccant materials have the capability to remove or add moisture adiabatically—a reversible thermodynamic process wherein energy exchanges result in substantially constant enthalpy equilibrium. The total desiccant open cycle is somewhat similar to a refrigerant vapor-compression cycle. In a desiccant and air system, the heated regeneration air adds energy to the moistened desiccant in a desorption process and releases moisture in the regenerating crossing air stream in an adiabatic cooling process. When the desiccant rotates to the process air stream, the pre-conditioned desiccant enables the absorption of water and dehumidifies the crossing process air. Adiabatic re-heat is released in the air stream. This completes the desiccant vapor-compression open cycle.

Some systems use a re-circulating air stream: crossing a first desiccant rotor zone; flowing through a cooling element; and re-circulating through a second desiccant rotor zone. Other system use the condenser re-heat in a same air stream to provide a heating drying effect or to accommodate circumstances of having to dissipate the energy somewhere. In these systems, the process air flows through a sector where the desiccant rotor is pre-conditioned to release vapor pressure into the crossing air stream. The augmented saturated conditioned air then flows through a typical evaporator coil which removes the vapor by a condensation process. The air usually leaves this coil near saturation and the second part of the rotor capture the vapor and the air leaves dryer and partly heated through a desiccant adiabatic process occurring. The rotor rotates bringing the captured vapor to the other zone. If a condenser is in series with the air stream, then the air is re-heated.

Other similar systems also utilize devices with similarities to the rotor but have more sensible energy exchange capabilities. Apparatuses such as sensible heat rotors, heat pipe systems (and concept) and also heat plates are devices having an ability to exchange heat from one air stream to another until reaching an equilibrium. These devices are not limited to sensible heat exchange but can also interchange latent energy and vapor.

These sensible heat exchange devices and apparatus are often utilized for dehumidification in the scenario that the heat exchanger pre-cools the process entering air crosses a refrigerant evaporator. The air leaving the evaporator crosses an adjacent side of the heat exchanger which the device re-heats the delivery air. A refrigeration condenser re-heats the air additionally in the leaving process air stream.

Bypass air can be utilized to additionally cool the condenser heat to maintain lower refrigerant condensing pressure resulting in augmented efficiency.

In the refrigerant compression closed cycle of the conventional air conditioning system, a compressor compresses refrigerant gas to increase its pressure and temperature in an isentropic adiabatic process. The refrigerant is then passed through a condenser coil where the superheated compressed refrigerant dissipates its heat to the crossing air stream, condensing the refrigerant into a high-pressure liquid which then flows through a metering device or expansion valve that restricts the high-pressure liquid and creates a reverse refrigerant adiabatic effect. After which, the refrigerant is discharged or suctioned to an evaporator coil at lower refrigerant temperature and pressure than that of the evaporator coil. This enables the evaporator coil to absorb heat from the crossing air that is forced past the coil by the evaporator fan of the conventional air conditioning system. The air exiting past the evaporator coil is discharged as cool air and the refrigerant absorption process changes the refrigerant from vapor to gas. The refrigerant is then suctioned back to the compressor to complete the closed cycle.

Typically, most dehumidifiers and dehumidifier systems cool a process air to remove vapor using a typical refrigeration coil, re-heating the air with condenser energy in the same air stream. In these systems, the air needs to be cooled to a dew point and, afterward, any additional cooling will result in the removal of vapor by both condensation and sensible energy. The latent to sensible energy ratio diminishes the effectiveness of these system especially if the intake air is not saturated. Other air conditioning systems optionally utilize condenser re-heat, on demand, and enabled through the use of additional refrigerant valves and coil arrangement to force the system to operate without a sensible cooling effect but while, at least, providing dehumidification. These systems do not necessarily reach an optimally low dew point, due to risk of frost and waste energy, by having to continuously re-cool the entering air back to a coil dew point.

In the air-cooling process, a conventionally finned evaporator coil provides dehumidification only if the saturated vapor conditions are achieved in its crossing air and additional cooling is typically necessary to augment moisture removal. This accomplished by lowering the refrigerant pressure and temperature by increasing the compressor capacity or lowering the crossing air stream volume in the evaporator. Efficient heat transfer of a coil is dependent upon the temperature differential between the refrigerant temperatures relative to the temperature of the crossing air. The accumulation of water on the evaporator fins serves as an excellent conductor for transferring heat energy to its crossing air stream. The temperature of the water on the fins tends to become lower quickly, because of its direct conductive energy exchange, and at lower temperatures it consequently crystallizes and freezes. This causes the fins to exhibit properties of an insulator. These properties diminish energy transfer capabilities and effectiveness. Ice buildup on the fins can also restrict the air path and further diminish the conductive thermal energy transfer capabilities and efficiencies of a refrigerant.

For a given set of conditions, the compressor power and the refrigeration capacity of a refrigeration system is very much affected by the condensing pressure. The higher the condensing pressure, the smaller the refrigerating capacity and the greater the compressor power usage.

Dehumidification using vapor compression refrigeration bears similarities to a conventional refrigeration system except for there being a condenser coil being placed downstream from the evaporator coil, that reheats air that has been cooled and dehumidified. There are several important processes to consider:

Superheated discharge line vapors of refrigerant are circulated from a evaporator coil pursuant to a refrigerant condensation process. The refrigerant condensing process changes the refrigerant state from vapor to liquid. In accordance with known properties of de-superheat and sub-cooling, this results in the dissipation of heat, by the evaporator coil, which serves as a heat exchanger, in connection with a crossing air stream over the evaporator coil. The liquid refrigerant from a condenser flows through a metering device or expansion valve that restricts the high-pressure liquid and creates a reverse refrigerant adiabatic effect, after which, the refrigerant is discharged or suctioned to the evaporator coil containing the refrigerant at a lower temperature and pressure than that initially coming from the condenser. This enables refrigerant, within the evaporator coil, to absorb heat from the crossing air that is forced past the evaporator coil by an evaporator fan. The air exiting past the evaporator coil is discharged as cool air and the refrigerant absorption process changes the state of the refrigerant from liquid to vapor, which is then suctioned back to the compressor to complete the closed cycle.

An expansion process occurs in connection with the sub-cooled high pressure liquid approaching a metering device. In connection with liquid being expanded into the evaporator coil (evaporator) through an output orifice (serving as part of a metering control), the temperature and pressure of the refrigerant liquid is reduced in comparison with the pressure and temperature during condensing of the condensation process.

The refrigerant evaporation process accounts for the most significant amount of energy exchanged in connection with a crossing air stream over an evaporator coil containing a refrigerant. The refrigerant, in this process, evaporates water and absorbs heat energy, simultaneously, from the crossing air stream which results in the cooling process of that air. Superheat enables energy exchange to have sufficient energy differential between the refrigerant and the air crossing stream. Most of all, superheat conditions the refrigerant to be in a suitable condition prior to entering the compressor, so as to prevent slugging of liquid refrigerant which could result in damaging the compressor. If superheat provides effective cooling, then the energy gained by superheat ads to the compressor performance ratio.

For a given set of conditions the compressor power, and to a lesser extent the refrigeration capacity, of a refrigeration system is very much affected by the evaporative pressure. The lower the evaporative pressure, the smaller the refrigerating capacity and the larger the compressor power.

Typically, in an evaporator heat exchanger, the exchange of energy between the refrigerant and its crossing air stream is of a conductive nature and creates a unfavorable situation of frost when attempting to get a conditioned air to a lower dew point.

In the air-cooling processes, a conventional finned evaporator coil provides dehumidification only if the crossing air temperature and saturated vapor conditions are first achieved and additional cooling is typically necessary to augment moisture removal. This may be accomplished by lowering the refrigerant pressure and temperature by increasing the compressor capacity or lowering the crossing air stream volume in the evaporator. Efficient heat transfer of a coil is dependent upon the temperature differential between the refrigerant temperatures relative to the temperature of the crossing air. The accumulation of water on the evaporator fins serves as an excellent conductor for transferring heat energy to its crossing air stream. The temperature of the water on the fins tends to become lower quickly, because of their direct conductive energy exchange, and at lower temperatures it consequently crystallizes and freezes, thereby becoming an insulator, something that diminishes energy transfer capabilities and effectiveness. A resulting ice buildup can also restrict the air path and further diminish the conductive thermal energy transfer capabilities and efficiencies of the refrigerant.

Conventionally, there are several methods used to defrost coils. These methods are often used in refrigeration scenarios. For instance, a method using a timer or a pressure or temperature sensor recognizing the ice buildup, may cause the refrigeration process to pause the cooling process should the air temperature of a coil reach a certain temperature. Other methods include: hot refrigerant gas bypass; and pushing refrigerant hot gas into the evaporator coil (which stops the coil fan and therefore defrosts the coil). An electric heater may be used in a similar man in the case of freezing coils.

Heat recovery ventilator (HRV) and energy recovery (ERV) technology are utilized for fresh air, better climate control, energy savings and vapor recovery. Typically, a HRV or ERV is a device built for efficient heat transfer or heat and latent heat (vapor) transfer from one air stream to an adjacent crossing air stream through a medium. These devices are often used in the HVAC industry and for energy recovery between gases and or as a concentrator of certain gases.

In colder climates and winter mode of operation, HRV do require a defrost method since in winter mode of operation the heat exchanger tends to freeze. The outdoor air coming into the heat exchanger being lower than the freezing point tends to freeze up the humidity of the outgoing air.

The frost then restricts the air flow and provide an insulation factor on the heat exchanger face surface diminishing energy exchange effectiveness.

In most occurrences the present technology utilizes a heater or re circulating indoor air to enable defrost occurrences. This is usually accomplished by cycling. Heat exchangers are mostly counter flow or cross flow. Nonetheless they work on the basic principle of having two adjacent air streams sliding on a heat exchange surface enabling heat transfer to occur.

Heat recovery ventilator (HRV) and energy recovery (ERV) technology are utilized for fresh air, better climate control, energy savings and vapor recovery. Typically a HRV or ERV is a device built for efficient heat transfer or heat and latent heat (vapor) transfer from one air stream to an adjacent crossing air stream through a medium. These devices are often used in the HVAC industry and for energy recovery between gases and or as a concentrator of certain gases.

Air to air heat exchangers usually constructed of several plate type or membrane surface and are known as counter flow or cross flow. These air to air heat exchangers generally operate on the basic principle of having several air paths any two of which adjacent air streams sliding past each other on a heat exchange plate surface enables heat transfer or energy transfer to occur through the walls of the heat exchange surface. Plate types made of, for instance, metal or plastic, facilitate the transfer of heat such as causing a heat or cooling effect in an adjacent air stream. Plate types made of substrate, wicking, or porous material also additionally can transfer latent energy, causing a dehumidification or humidification process in an adjacent crossing air stream.

In colder climates and winter mode of operation, HRV (heat recovery ventilator) do require a defrost method since in winter mode of operation the heat exchanger surface plate tends to freeze up. The outdoor air coming into the heat exchanger may have a below zero-degree C. temperature, which tends to freeze up the humidity of the outgoing air, such that frost or ice forms in the outgoing air channels. The frost then restricts the air flow and also provides insulation on the heat exchanger face surface, diminishing energy exchange effectiveness. FIG. 1A, illustrates a process flow involving entering air stream 1, passing through cross flow heat exchanger 10. In heat exchanger 10, air stream 1 changes to an air stream arrangement of several air streams to flow in a cross flow arrangement crossing the heat exchanger 10 and leaving heat exchanger 10 as rejoined air stream 3. The passing air transfers its heat through the plate surfaces of heat exchanger 10 to its adjacent air streams. This is achieved through an arrangement involving any two of its adjacent air streams sliding past one another on a heat exchange plate surface, thereby enabling heat transfer (energy) to occur through the walls of the plate surfaces of heat exchange 10.

FIGS. 1B through 1E represent further process flows through an air exchange. Intake air stream 1, which is to be dehumidified, is hot humid air, elevated both in heat and vapor pressure passing through crossflow type-heat exchanger 10. However, the cross flow is contemplated as involving other types of heat exchangers such as U-type heat exchanger 20 (FIG. 1B), Z-type heat exchanger 30 (FIG. 1C), L-type heat exchanger 40 (FIG. 1D) and cross-counter flow-type heat exchanger 50 (FIG. 1E).

FIGS. 2A through 2E represent process flows through an air exchange in connection with dehumidification. FIGS. 2A through 2E illustrate a line diagram showing air to an air heat exchanger in a cross-flow air process arrangement similar to that of FIGS. 1A through 1E, but with the addition of a cooling coil 60 which may provide dehumidification in connection with air to air heat exchangers that can be co-joined to a refrigeration cooling, or water cooled coil and system, to perform as dehumidifiers.

In the process flow scenarios depicted by FIGS. 2A and 2C, 2D and 2E, through an energy exchange process, air stream 3 is pre-cooled prior to crossing cooling coil 60 in connection with its adjacent air stream 4 and it is pre-conditioned to a lower and augmented vapor pressure condition prior entering the cooling coil 60. Should air stream 3 reach its dew point, condensation will also occur within a respective heat exchanger (10, 20, 40, 50). Pre-cooled air stream 3 crosses cooling coil 60 and it is additionally cooled, providing a lowered dew point. The resulting vapor is condensed and removed or collected. Cooler adjacent air stream 4, shown as leaving the coil 60, in FIGS. 2A, and 2C through E, reenter air to a respective heat exchanger (10, 40, 50).

Adjacent air stream 4 which represents dehumidified leaving air cooling coil 60 will be re-heated in the same energy ratio as air stream 3 shown as leaving and being cooled by a respective heat exchanger (10, 40, 50) and its associated heat exchange process. Thusly, air stream 1 is dehumidified by both an associated heat exchanger cooling effect and cooling coil 60. The process of pre-cooling the air stream 3 prior entering the cooling coil 60 saves on the amount of energy needed for dehumidification.

It is standard practices to have the heat exchanger units or dehumidifier as standalone units, attached to a ducting system or attached as a bypass in the return air duct of a central air distribution system. The foregoing process flows may be used therewith.

The processes shown in FIGS. 2A through 2E, outperform that of most conventional dehumidifiers and cool a process air to remove vapor using a typical refrigeration coil followed by re-heat of the air with condenser energy in the same air stream. For an air-cooling process, the conventional finned evaporator coil provides dehumidification only if the saturated vapor conditions are achieved by its crossing air and additional cooling is typically necessary to augment moisture removal.

The foregoing, and other features and advantages of the invention, will be apparent from the following, more particular description of the preferred embodiments of the invention, the accompanying drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, the objects, and advantages thereof, reference is now made to the ensuing descriptions taken in connection with the accompanying drawings briefly described as follows.

FIGS. 1A through 1E represent process flows through an air exchange.

FIGS. 2A through 2E represent process flows through an air exchange in connection with dehumidification.

FIG. 3 is a line diagram illustrating a process flow showing a first cooling coil coupled to intake air and air path from first cooling coil.

FIG. 4 is a line diagram view showing a first system in cascade sequence to a second dehumidification system which includes an air-to-air heat exchanger and dehumidification process.

FIG. 5 is a line diagram illustrating a process flow scenario showing the delivery of air in several air streams and to adjacent air streams that do not have a dehumidifier option.

FIG. 6 is a line diagram illustrating a process flow scenario having dampers installed in an air path to restrict air flow, within a vent system, forcing air to flow through the dehumidification system as provided herein.

FIG. 7 illustrates a line diagram illustrating an exemplary process flow according to the foregoing. An air path may bypass the air exchange and dehumidification systems and provide air to blower(s).

DETAILED DESCRIPTION

The following provides a dehumidification system or unit in a cascade arrangement downstream to an air conditions system. More particularly, this may provide a dehumidifier in a sequence flow of delivery air of a cooling system. This dehumidifier may, for instance, include any type of air-to-air heat exchanger that enables the focus of its cooling to be towards latent energy.

Pre-cooling air processed through a dehumidifier prior to its entering the vicinity of a cooling coil saves on the amount of energy needed for dehumidification and serves to lower the associated dew point.

FIG. 3 is a line diagram illustrating a process flow showing a first cooling coil 9 coupled to intake air 8 and air path 12 from first cooling coil 9. Intake air 8 provides air to first cooling coil 9 which pre-cools air to a lower temperature resulting in a higher relative humidity. Air path 12 becomes the air stream 1 that enters heat exchanger 10 prior to a process of dehumidification provided in connection with cooling coil 60.

First cooling coil 9 is may be configured to handle sensible cooling in addition to dehumidification. Separating or decoupling the cooling process enables a first system to mostly deal with sensible cooling (and maximizing sensible cooling by design) and a second system implement by cooling coil 60 which enables a focus on proper dehumidification (using energy in connection with a latent load at a reasonable dew point.

The air entering the vicinity of first cooling coil 9 causes preconditioning of the air on air path 12 at a favorable condition prior to entering an air exchanger such as air exchanger 10.

With reference still to FIG. 3, air in air path 12, which leaves the vicinity of a first cooling coil 9, may be cooled to a certain extent leaving air, conditioned, but with a need for additional dehumidification. This pre-cooling by first cooling coil 9 allows air exchanger 10 to operate at a higher temperature than usual.

The refrigerant evaporation process represents the most significant amount of energy exchanged from the crossing air stream to the refrigerant. The refrigerant in this process evaporates and absorbs, simultaneously, the heat energy from its crossing air stream which results in the cooling that air.

For a given set of conditions, the compressor power, and to a lesser extent, the refrigeration capacity, of a refrigeration system is very much affected by the evaporative pressure. The higher the evaporative pressure, the greater the efficiency of that system. Therefore, having a first system operating without the need for dehumidification augments the efficiency of that first system, significantly.

Air in air path 12 may be cooled to a low temperature and with a high saturation point, and if the dew point is reached, some dehumidification will occur in the cooling element 9.

As shown in FIG. 3, air path 12 leads to airstream 1 which serves as the air intake to an air exchanger, such as heat exchanger 10. Return feed 2 represents the path of dehumidified air returning warmed through a heat exchanger such as heat exchanger 10.

The process shown in FIG. 3, outperforms, most conventional dehumidifiers which cool a process air to remove vapor, with a typical refrigeration coil and then re-heats the air with condenser energy in the same air stream. In the air-cooling process, a conventionally-finned evaporator coil provides dehumidification only if saturated vapor conditions are achieved in connection with crossing air. Additionally, further cooling is typically necessary in order to augment moisture removal.

Having the air (12) preconditioned to a lower temperature and augmented saturation enables the cooling coil 60 to operate at a lower temperature as compared to the initial coil (9) therefore operates at a lower evaporator pressure.

The refrigerant evaporation process is the most significant amount of energy exchanged from the crossing air stream to the refrigerant. The refrigerant in this process evaporates and absorbs simultaneously the heat energy from its crossing air stream and results in the cooling process of that air.

For a given set of conditions the compressor power, and to a lesser extent the refrigeration capacity, of a refrigeration system is very much affected by the evaporative pressure. The lower the evaporative pressure then the lesser the efficiency of that system.

A system including the heat exchanger 10 and cooling coil 60 with the capacity to recover the sensible cooling results in a lower dew point as compared to that involving first cooling coil 9. Such a system becomes efficient for the reasons that less energy is used to cool air and because cooling capacity is used to dehumidify at a lower dew point as compared that of the first cooling coil 9. It is noted that first cooling coil 9 may provide dehumidification or additional dehumidification.

The overall system is greatly improved through use of first cooling coil 9. Energy is saved as a result of the dehumidification process used. Further, cooling may be decoupled into a sensible cooling. This allows zooming in on the right cooling process in order to reduce over-cooling and allowing the use re-heat as an alternative to keeping air conditioner turned on. Cooling coil 9 may also provide cooling even in instances where an air conditioner is not operating.

If frost occur in the air exchanger 10, then the initial unit can be controlled to defrost or air exchanger 10.

FIG. 4 is a line diagram view showing first system 11 in cascade sequence to a second dehumidification system 100 which includes an air-to-air heat exchanger and dehumidification process. First system 11 may provide both the sensible cooling and dehumidification. Consequently, there are efficiencies corresponding to separating or decoupling a cooling process that enables the first system 11 to mostly deal with sensible cooling (and maximizing it design) and having a second dehumidification system 100 that enables a focus on energy with respect to a latent load at a reasonable dew point and being capable of properly dehumidifying. Nonetheless first system 11 may still be designed to dehumidify. First system 11 and dehumidification system 100 may be provided as a separate system which is attached to ducting within a structure.

System 11 also preconditions the air on air path 12 at a favorable condition prior entering dehumidification system 100.

With reference still to FIG. 4, air on air path 12 leaving a first cooling coil 9 may, conditioned to a certain extent, but without having maximized dehumidification. This allowing this dehumidification system 100 to operate at a higher temperature than usual.

The refrigerant evaporation process is the most significant amount of energy exchanged from the crossing air stream to the refrigerant. The refrigerant in this process evaporates and absorbs simultaneously the heat energy from its crossing air stream and results in the cooling process of that air.

FIG. 5 is a line diagram illustrating a process flow scenario showing the delivery of air in several air streams (13,14 EXT) and to adjacent air streams (15,16 EXT) that do not have a dehumidifier option. The process flow shown in FIG. 5 reflects the pre-cooling as noted with respect to FIG. 3. An option is contemplated which in connection with the stopping of air flow in first system 11, air paths (15,16 EXT) serve as return ducting for air intake air. It is also contemplated that return air 2 (delivery air) occur in the same area or vicinity of air streams (15,16 EXT.).

FIG. 6 is a line diagram illustrating a process flow scenario. As shown, dampers 41 and 42 may be installed in an air path to restrict air flow, in vent system 40. Air path 43 reflects the path of air flowing from return feed 2 after damper 42.

FIG. 7 illustrates a line diagram illustrating an exemplary process flow according to the foregoing. Air path 61 may bypass the air exchange and dehumidification system and provide air to Blower(s) 62 is contemplated as being used facilitate air flow along air stream 1 and airstream 4 as shown in FIG. 7. Air on air path 61 may be added to air on return feed 2 to flowing along air path 43.

It is an option to enable through these controls feature the option of controlling the ratio of latent energy removal verso sensible having control over a function of dehumidification and or sensible cooling effect. It is a further option to either modulate a fan speed or control a fan speed using variable speeds (such as a three-speed motor). Additionally, it is also an option to modulate the cooling capacity or have step down control such as dual compressor scenario or a refrigerant valving causing the same effect as compared to modulation. Further, the return feeds from the dehumidifier shown in the drawing figures may also be representative of a control feedback loop from the dehumidifier, in a feedback system, allowing control of the operation of pre-cooling through first cooling coil 9. The feedback system may be configured to control the operation of the pre-cooling in connection with operating conditions detected at the dehumidifier. It is further contemplated that the foregoing described pre-cooling may be used in connection with a plurality of process air paths within a building structure to a plurality of dehumidifiers with the building structure.

The foregoing has been described herein using specific embodiments for the purposes of illustration only. It will be readily apparent to one of ordinary skill in the art, however, that the principles of the foregoing can be embodied in other ways. Therefore, the foregoing should not be regarded as being limited in scope to the specific embodiments disclosed herein, but instead as being fully commensurate in scope with the following claims. 

I claim:
 1. A system for control of humidity, comprising: a dehumidifier; a heat exchanger coupled to the dehumidifier; a first pre-cooler coupled to the heat exchanger, the pre-cooler being configured to pre-cool process air prior to the entry of the process air into the heat exchanger; and a return feed coupled to the heat exchanger configured to receive process air from the dehumidifier.
 2. The system for control of humidity as recited in claim 1 which further includes one or more dampers, within the flow path of the process air, which are configurable within the flow path to restrict air flow in the flow path.
 3. The system for control of humidity as recited in claim 2 wherein the first pre-cooler contains a refrigerant for circulation therethrough.
 4. The system for control of humidity as recited in claim 1 wherein the heat exchanger is selected for the group consisting of a D-type, Z-type, L-type and cross-counter flow-type heat exchanger.
 5. The system for control of humidity as recited in claim 1 which further includes feedback system, coupled to the dehumidifier and first pre-cooler, the feedback system being configured to control the operation of the first pre-cooler in connection with operating conditions detected at the dehumidifier.
 6. The system for control of humidity as recited in claim 1 which further includes one or more blower fans located on a path for process air flow between the first pre-cooler and the dehumidifier.
 7. A method for control of humidity, comprising: pre-cooling process air prior to send the process air through a heat exchanger; directing the process air, from the heat exchanger, through a dehumidifier; and directing air from the dehumidifier through the heat exchanger so as to provide a return path from the dehumidifier.
 8. The method for control of humidity as recited in claim 7, which further includes controlling the operation of the pre-cooling in conjunction with operating conditions at the dehumidifier.
 9. The method for control of humidity as recited in claim 7 wherein pre-cooled process air is provided to a plurality of process air paths within a building structure to a plurality of dehumidifiers with the building structure.
 10. The method for control of humidity as recited in claim 9 wherein one or more humidifiers from the plurality of dehumidifiers may control the operation of the pre-cooling at a respective dehumidifier in conjunction with operating conditions at the respective dehumidifier.
 11. The method for control of humidity as recited in claim 9 which further includes providing one or more damper, for restricting the flow of pre-cooled process air or humidified air from a return feed. 